In the first of the new series, Charlie's in south London, where self-building duo Caroline and Chris are hoping to deliver an urban marvel on a tight plot, and a tighter budget. Chris is an architect, so you'd think achieving perfection on time and on budget should come second nature. But a string of budget-busting gremlins suggest this build has other ideas. And just when they think things can't get any more complicated, life throws them a curveball which racks the pressure even higher.